2. • In order to represent accessibility
information digitally, we have to break
down the real-life environment into its
discrete features (objects, elements) :
- Stairs
- Ramps
- Corridors, etc.
2
3. • Each object has a set of properties
(attributes) describing it from the viewpoint
of accessibility:
- eg. a ramp has a particular slope
(inclination) and width that make it
(in)accessible for a wheelchair user
3
4. Outdoor objects and accessibility
attributes
Outdoor Object
Attributes
Ramps
Width
Inclination
Handrail
Manoeuvrin
g Space
Steps
Lighting
Coloured
Markings
Tread Depth
Handrail
Pathways
Surface
Inclination
Parking Space
Number of
Places for
Wheelchair
Distance to
Entrance
Building
Wheelchair
Accessible
Width
Automatic
Opening/Closing
Bell /
Intercom
4
6. Description sheets
for each type of object – outdoor or indoor
-‐ after creating (or finding) a digital element to represent a real-life
object, make note of its ID as well as values for its attributes
a8ributes
element
ID
retrieved
from
OpenStreetMap
/
indoor
mapping
app
a8ribute
value
a8ribute
values
can
be
numbers
or
sets
of
predefined
opBons
(eg.
good/poor/none):
see
file
“Kriterien”
for
possible
values)
6
7. Objects in OpenStreetMap (OSM)
• OSM lets us create digital
representations of outdoor objects
• Real-life objects are represented in OSM
by using geometric elements:
- points (known as ‘nodes’ in OSM)
- lines (‘ways’), and
- areas (‘closed ways’)
• Each element can be described (‘tagged’)
to store info about attributes of the
represented object
7
9. Desktop OSM: JOSM
• 1. Download current map data from
OpenStreetMap
• 2. Edit map elements using satellite
imagery, GPS, field papers and notes as
well as using our knowledge of a place
• 3. Save changes to OpenStreetMap
9
10. Nodes in OSM
• Nodes in OSM are point elements.
• They define a single geospatial point,
using a latitude and longitude.
10
11. Ways in OSM
• Way is a general term for a series of
joined nodes.
• They usually represent linear objects
(vectors), such as rivers or roads.
• Ways can also represent solid polygons
(areas), such as buildings or forests. In
this case, an area is a way whose first and
last node are the same – a closed way.
• Closed ways occasionally represent linear
loops, such as highway roundabouts,
rather than solid ('filled') areas.
11
12. Tags in OSM
• All elements have tags that describe the
objects that the elements represent in
more detail.
• Tags are organized into keys and values.
The general form of a tag is key=value.
• Keys are categories of object properties,
such as Land Use for a closed way
representing a plot.
• Values specify keys, eg.
Land Use=Garden
12
13. Example: representing steps (and ramps)
in OSM
• After entering a line (‘way’ in OSM) to
represent the steps, we need to tag it
appropriately:
• highway=steps: “highway“ is a key describing
what kind of linear element the way is
• incline=20%: “incline” is a key to store the
slope
• ramp=yes: if the way represents a ramp
rather than steps, this tag is needed
• handrail=yes: is there a handrail?
• etc.
13
14. Tags in OSM
• There are numerous tags available –
check the links for a description of what
different keys and values mean
- https://www.openstreetmap.org/login?
referer= %2F
- http://learnosm.org/en/beginner/start-osm/
• To store accessibility information, we can
use some of the available tags; eg.
width=120cm
14
15. Accessibility-related OSM tags
Outdoor
Object
A-ributes
Ramps
highway=steps
ramp=yes
Width
width=*
InclinaBon
Handrail
Manoeuvring
incline=*
handrail=yes/ Space
no
Steps
highway=steps
LighBng
Coloured
Markings
Pathways
highway=””
Surface
surface=””
InclinaBon
• eans
that
the
value
for
the
m
incline=*
key
has
to
be
numerical
Tread
Depth
Handrail
handrail=yes/
no
Parking
Space
Number
of
Places
Distance
to
“”
means
that
the
value
for
amenity=parking
for
Wheelchair
Entrance
the
key
is
a
string
of
characters
capacity:disabled=
yes/no/number
Building
Wheelchair
building=entrance
Accessible
wheelchair=yes/
limited/no
Width
width=*
AutomaBc
Opening/
Closing
Bell
/
Intercom
15
16. • What about accessibility attributes for
which keys are not already available in
OSM?
• Use description=“” tag, eg.
decription=manoeuvring space available
• In any case, adding tags in OSM is
welcome but optional: all accessibility
attributes should be entered in description
sheets (slide 6)!
16
23. Thank you and have fun!
• Contact us for any questions and doubts:
• Elisabet Adeva:
e_adev01@uni-muenster.de
• Nemanja Kostic:
kostic_nemanja@yahoo.com
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